There's a world of difference between "wilderness" and "frontier." I freely acknowledge that there are mountains where you ski or hike for miles without seeing anyone. At the same time, they're the same mountains where your ancestors have been skiing or hiking for miles since before the advent of written language. The culture of Scandinavia has been Scandinavian since before the Etruscans; neither the Romans nor the Mongols so much as set foot there. By contrast, I grew up in a place where the houses were built on the roaming lands of nomadic tribes that were kicked out for once and for all at a time when their leaders were studied by anthropologists from Washington and their artifacts were shipped to the Smithsonian. Your definition of "frontier" is not the definition of "frontier" and that parameter mismatch is important.